1. Technical Field
The present invention relates to a control system including a main control device and a sub-control device for monitoring an operational state of the main control device, and relates to an electric power steering control device using the control system.
2. Background Art
As known in a conventional art, an electric power steering control device is explained as a system by which steering power of a power is reduced by using driving power for a motor, which is used as auxiliary power. However, a microcomputer is used for controlling the motor, and abnormal auxiliary power is generated when an abnormality occurs in the microcomputer, and the auxiliary power is objectionable for a safety operation. Therefore, a reliability of the microcomputer becomes more important, and a countermeasure for the reliability of the microcomputer, by which safety is ensured even when the microcomputer is abnormally operated, is implemented.
In order to realize control systems used for the above-described electric power steering control device, a conventional control system is suggested, in which a microcomputer operated as a main control device and a sub-control device for monitoring an operational state of the main computer are included, and when the operation state of the main computer is abnormal, the sub-control device detects the abnormality so as to stop the operation of the main control device.
For example, the conventional control system described in Japanese Laid-Open Patent Publication No. 2009-132281 includes a main computing device connected to an in-car LAN, a sub-computing device connected to the in-car LAN, and a communication device for communicating between the main computing device and the sub-computing device, and then, the sub-computing device detects an abnormality of the main computing device by comparing information transmitted from the main computing device via the communication device with information obtained from the in-car LAN.